Plastic footwear such as ski boots and boots for skates, collectively referred to herein as boots, are usually comprised of two, three or four parts necessary to permit flexing of the ankle forward and backwards while retaining lateral support for performance. These plastic parts are normally connected with metal rivets, permitting swiveling or rotation around the location of the rivets. Plastic is commonly used and the parts are formed by such methods as injection molding. The boot provides protection to the foot and lower leg and adds sufficient stiffness to permit good performance such as in ski boots where lateral support is necessary for various ski maneuvers.
It is necessary when skiing or skating to permit the skier or skater to bend his or her knees in the forward direction and to encounter various resistance as the knee is bent further forward, eventually coming to a stop, before damage occurs to the Achilles tendon. This requires fairly precise fit of the plastic pieces and careful placement of rivets or other pivoting means to provide for comfort and performance at the same time.
Normally a boot of the above described type has a lower shell having a heel, middle and front section for receiving and supporting an individual's foot along the heel, bottom, sides and top front portion of the foot. The boot may also include a cuff which covers the upper portion of the foot or lower leg. The cuff is the part which rotates forward when the knee is bent. Additionally, many boots have tongues or rear portions which permit exit and entry in the case of front-entry or rear-entry boots.
Conventionally constructed boots utilizing rivets are limited in that the cuff or other plastic parts attached to the lower shell must rotate around a fixed point. This is not necessarily compatible with the human foot, which has a semi-sliding joint in the ankle rather than one which pivots from a point between the ankle bones.